Abstract During childhood, self-regulation underlies children?s ability to cooperate, follow directions, control impulses, and manage upsets which in the long-term leads to fewer physical and mental health problems, greater academic success, higher socioeconomic status and income, and fewer arrests. Thus, understanding the developmental processes and facilitating mechanisms leading to self-regulation, is a critical public health concern. The development of self-regulation is even more important for children exposed to chronic contextual stress, such as Mexican origin (MO) children. Yet considering the importance of self-regulation, and the rapidly growing number of MO children, there is a surprising dearth of information on child development processes in this population. Parents are thought to be a primary socializing agent for self-regulation; therefore we aim to examine how MO parents foster self-regulation, the impact of contextual stressors, and the protective and promotive role of parental and cultural characteristics. To do this, families will be recruited from the California Family Project, an ongoing longitudinal study of MO families (N = 674) that initiated in 2005. Target individuals are now approximately 19 years old and are beginning to have their own children (currently, N = 45). Families will be assessed when their child is 6, 18, and 36 months old. At each time point parents will complete ecological momentary assessments (EMA) of parent-child interactions and collect cortisol samples on themselves and their child across multiple days. Home visits will also be conducted at each time point to assess contextual stress, global family interaction patterns, and the child?s emotional, behavioral, and cognitive regulation. An EMA study is particularly critical in determining how family interactional patterns are established, how family members connect and conflict, and how the ebb and flow of family life as it is lived is impacted by daily stressors, moods, and physiology. Aims will examine 1) whether parental dysregulation mediates the association between parent?s contextual stress and their child?s self-regulation; 2) the dynamic transactions between parents and their children across the day and week, and from year to year leading to children?s self-regulation; and 3) parent?s cultural and psychological resilience factors. This portion of the project is considered ?phase 1?. We have long-term plans (phase 2) to to follow these families into elementary school to understand the implications of contextual stress, parenting, and self-regulation on school readiness and achievement. Thus, phase 1 will focus on the parent?s socialization of regulation and the influence of contextual stressors, phase 2 will extend these findings to examine the implications for school readiness. Early acquisition of the self-regulatory skills being studied is an important element in life long academic success, and uncovering pathways of self-regulatory development could inform prevention and intervention efforts. Early identification and prevention have been shown to provide the most short- and long- term benefits and the highest economic returns. Moreover, the examination of cultural and psychological protective factors increases the likelihood that this study will inform targeted and culturally relevant intervention and prevention strategies.